Enter Solar Planning Inputs
Results appear above this form after submission.
Example Data Table
| Scenario | Monthly Use (kWh) | Sun Hours | PR (%) | Panel Wattage | Estimated Size (kW) |
|---|---|---|---|---|---|
| Small Home | 450 | 5.2 | 78 | 450 | 3.69 |
| Medium Home | 900 | 5.5 | 80 | 550 | 6.82 |
| Large Home | 1500 | 5.8 | 82 | 600 | 10.52 |
| Office Unit | 3000 | 6.0 | 79 | 600 | 21.10 |
Formula Used
Daily Energy Use = Monthly Energy Use ÷ 30
Adjusted Daily Need = Daily Energy Use × (1 + Safety Margin)
Required Solar Capacity (kW) = Adjusted Daily Need ÷ (Sun Hours × Performance Ratio)
Panel Count = Required Solar Capacity ÷ Panel Size in kW
Installed PV Size = Panel Count × Panel Size in kW
Daily Solar Output = Installed PV Size × Sun Hours × Performance Ratio
Battery Storage = Daily Critical Load × Backup Days
Battery Capacity (Ah) = Battery Storage in Wh ÷ System Voltage
Roof Area Needed = Panel Count × Panel Area
Annual CO₂ Offset = Annual Solar Output × CO₂ Offset Factor
How to Use This Calculator
Enter your average monthly electricity consumption in kilowatt-hours. Use bills from several months for better accuracy.
Add the average peak sun hours for your location. This value strongly affects required solar size.
Set the performance ratio to account for system losses, dust, wiring, inverter efficiency, and temperature effects.
Provide panel wattage and panel area to estimate quantity and roof space requirements.
Use the safety margin for future demand growth or extra protection against under-sizing.
Add battery backup days and critical load percentage if you want storage planning for outages.
Submit the form to see results above the calculator, along with a graph and export options.
FAQs
1. What does this calculator estimate?
It estimates solar array size, number of panels, expected generation, inverter suggestion, roof area requirement, battery storage, and carbon offset using your demand and design assumptions.
2. Why is performance ratio important?
Performance ratio captures practical losses from heat, inverter inefficiency, cable loss, mismatch, dirt, and shading. A lower ratio means you need a larger solar array.
3. What sun hours should I use?
Use average peak sun hours for your site, not total daylight hours. Local solar maps, installer reports, and historical irradiance data help choose realistic values.
4. Does the calculator include battery sizing?
Yes. It estimates storage based on your chosen critical load share and desired backup days. It gives both kWh storage and approximate amp-hour capacity.
5. Can I use this for off-grid systems?
Yes, for preliminary planning. Still, full off-grid design should also check surge loads, autonomy days, depth of discharge, seasonal sunlight changes, and generator backup.
6. What if my roof area is limited?
If required roof area exceeds available space, choose higher-wattage panels, reduce demand, improve efficiency, or consider ground-mount installation.
7. Is inverter size always smaller than panel size?
Often, yes. Many systems use a DC-to-AC ratio above 1.0. This calculator suggests a practical inverter size, but final selection depends on design goals.
8. Are these results exact enough for purchasing?
No. They are planning estimates. Before purchasing, confirm shading, structural capacity, local codes, orientation, tilt, equipment specifications, and utility interconnection rules.